Before checking whether a third-party model API behaves like its advertised model, configure the same endpoint, model ID and API protocol you use in your application. A successful connection alone does not establish model authenticity.
1. Base URL — Copy the API base from your provider's integration documentation, including any required version prefix. Do not paste the dashboard URL or a full chat/completions or messages request URL. For example, if the provider documents a base ending in /v1, keep that prefix; do not add /v1 blindly.
2. API Key — Use a key issued for that exact provider and endpoint, with access to the model and enough quota for a verification run. Remove leading or trailing spaces. Verification sends requests through your key and may incur provider charges; use a limited key where your provider supports it.
3. Model ID — Copy the exact request model identifier, including any provider-specific alias or version suffix. A marketing name may differ from the identifier accepted by the API. The official reference model is a separate choice: confirm the model you intend to compare against instead of assuming an automatic suggestion is correct.
4. Protocol — Choose the request format your gateway documents. A Claude-branded model exposed through an OpenAI-compatible chat/completions API uses the OpenAI protocol. Choose Anthropic for an Anthropic-style messages API; the brand alone does not determine the protocol.
5. If connection fails — Check key permissions and quota for authorization failures, the documented base and model identifier for not-found responses, and the protocol for request-format errors. A handshake failure means the verification could not proceed; it is not evidence that the model is fake.
6. Read the result — A match means observed behavior agrees with the selected reference under the current checks. Mismatch or uncertainty needs context: routing, model versions and gateway behavior can affect the result. Compare repeated observations and your own workload before making a provider decision.